WASHINGTON – Battery problems that grounded Boeing's 787 Dreamliner for three months proved that government oversight works because nobody was hurt in the incidents and the planes didn't crash, federal and Boeing officials told a House panel Wednesday.

Peggy Gilligan, the Federal Aviation Administration's associate administrator for aviation safety, told the transportation subcommittee on aviation that safeguards that Boeing develops and FAA approves protect planes and passengers even if one part like a battery fails.

"We believe that this is a demonstration of a system really working well," Gilligan said. "The reality is these are complicated pieces of equipment and things will go wrong, but we need to make sure the plane can land safely and that's what we did."

The FAA and other regulators grounded the worldwide fleet of 50 planes in January after two planes suffered problems with lithium-ion batteries. But the planes are flying again after FAA approved Boeing's remedy to add insulation and covering to the batteries.

The hearing coincided with word of a couple of minor glitches with the Dreamliner.

An All Nippon Airways flight Wednesday in Japan was canceled when the right-side wouldn't start. On Tuesday, a Japan Airlines flight to Singapore returned to Tokyo's Haneda airport after takeoff because of a problem with the deicing system.

Mike Sinnett, chief project engineer for Boeing's 787, said the plane has been more than 98% reliable during the first 15 months of service. Battery testing has become even tougher since FAA initially approved the plane's electrical system after 25,000 hours of lab testing and 10,000 hours of testing under normal and abnormal operating conditions, he said.

"Our designs feature multiple layers of protection and redundancy of critical systems so that no single component failure of combination of failures – even extremely remote – can endanger an airplane," Sinnett said. "Flying is as safe as it is because industry and government work together day in and day out."

Lawmakers held the hearing to review lessons from the battery problems.

"This hearing is not about laying blame on anyone," said Rep. Frank LoBiondo, R-N.J., who heads the aviation subcommittee.

Gilligan told LoBiondo that no new laws were needed to ensure aircraft safety. But Gilligan said FAA plans to consult experts outside aviation in the future, after finding that battery experts could have added guidance in reviewing the Dreamliner's lithium-ion batteries.

"We are confident that the new design will protect the safety of the aircraft and its passengers," Gilligan said. "We believe the certification process is really quite robust."

Several lawmakers asked why rigorous testing never caught the battery problem before plane was in service.

"Why after all this testing did this problem not show up before?" asked Rep. John Duncan, R-Tenn.

Previous stress testing involved driving a nail into the battery. But while the plane was grounded, Boeing developed a tougher test by surrounding a battery with a heating element and forcing it to short-circuit.

To get the plane back in the air, Boeing forced a battery failure inside a plane while the engines and batteries were operating, Sinnett said.

"It demonstrated that even while that single cell failed, it continued to operate for the next hour and the airplane continued to operate normally throughout the entire event," Sinnett said.

The hearing comes at an important juncture for Boeing.

The Dreamliner's rival Airbus A350 is scheduled to take its first test flight Friday in France. Both planes are lightweight and designed to save fuel.

After the three-month hiatus in flights, Boeing is promoting the 787 with the appearance of two Dreamliners at next week's Paris Air Show. One will be flying while the other is on display.

Dreamliners were grounded Jan. 16 came after two battery incidents. An empty Japan Airlines plane in Boston caught fire Jan. 7 and an All Nippon Airways plane made an emergency landing because of a smoking battery Jan. 16.

While the National Transportation Safety Board continues looking for the cause of the Boston incident, Boeing took several steps to prevent a similar problem from occurring again.

FAA approved Boeing's remedy April 19 after the manufacturer inserted better insulation between each battery's cells to prevent overheating, covered each battery in a steel box to contain a possible meltdown and installed a titanium tube to carry smoke and electrolytes outside the plane if a battery does overheat.

Airlines returned the plane to the sky in recent weeks. United Airlines, the only U.S. carrier with the plane, returned with a flight May 20 from Houston to Chicago.